In the currently-evolving network environments, there is an increasing requirement for flexible connectivity between switching nodes for the carriage of payload, control and management traffic. Although switching nodes were once monolithic entities, they are more and more becoming complex distributed architectures which facilitate diversity in services and scalability in capacity. The rapid growth of packetized data traffic in LEC and IEC networks requires that switching nodes perform muli-layer switching functions and handle both connectionless and connection-oriented network traffic. Therefore, there exists a need for scalable routing and forwarding functions in a distributed switching architecture.
Both existing and evolving routing protocols such as Asynchronous Transfer Mode (ATM), Forum Private Network-Network-Interface Specification (PNNI), Internet Open Shortest Path First (OSPF), and International Standards Organization (ISO) Open Systems Interface (OSI) identify a network node by the identify of its Route Server Element (RSE) which is some form of global address. Each RSE generates a routing table based on a preferred performance metric and a most recent topological view of the network. The table thus creates optimal routes for communication throughout the network. The RSE is responsible for administration of the algorithms that enable a node to keep its view of the network topology and performance metric current, referred to as Routing Information Exchange (RIE). This combination of responsibilities often necessitates the need for the RSE to act as a central focus for the routing of traffic through the switching node. The consequence of this is that the RSE becomes a bottleneck resource limiting the capacity and scalability of a distributed switch architecture.
The impact of this bottleneck has been recognized and efforts to minimize its impact have resulted in the invention of intelligent input/output controllers which autonomously handle a portion of the packet routing function. Such controllers are described for example in U.S. Pat. No. 4,494,230 which issued on Jan. 15, 1985 to Turner, and U.S. Pat. No. 5,367,518 which issued on Nov. 22, 1994 to Newman. These patents respectively describe packet switching systems dedicated to connection-oriented traffic in which intelligent controllers request packet routing information from a central control unit only on call connection setups. The routing information supplied by the central controller is stored in a routing look-up table in controller resident memory. Thereafter, the controller uses the same routing information to route all packets associated with the call connection, thus freeing the central controller to attend to other functions. While this switching model improves the switch throughput of connection-oriented packet switching systems, it does not alleviate the central controller bottleneck for connectionless payload traffic. The exponential growth of packetized data traffic is now placing onerous switching burdens on network nodes. There therefore exists a need for a network route server having scalable routing and forwarding functions in a distributed switching architecture in order to supply the packet switching capacity now required.